Method and apparatus for testing production of high frequency cables

ABSTRACT

The production of HF cables is supervised by indicating speed deviations from the desired cable speed. Cable speed is represented by a pulse source providing pulses leaving frequency proportionate to cable speed, the frequency is converted into a voltage to be compared with a reference for indicator control.

United States Patent Klebl [4 1 June 27, 1972 54] METHOD AND APPARATUSFOR [56] References Cited TESTING PRODUCTION OF HIGH UNITED STATESPATENTS FREQUENCY CABLES 3,356,790 12/1967 Polizza'no et al ..l74/l02[72] Inventor: Wolfram Klebl, An Der Beeke, Germany 2,586,076 1952NiChOlS Assign: Kabehmd Memuwerke GutehoH- 3,51 1,151 5/1970 l-llllman..324/l6l X h tt Aktl llsch g r e Hanover Primary Examiner-Jerry W.Myracle Attorney-Smyth, Roston & Pavitt [22] Filed: Jan. 12, 1970 21Appl. No.: 2,056 [57] A RAC The production of HF cables is supervised byindicating speed [52] U.S. Cl. ..73/506, 324/168 deviations from thedesired cable speed. Cable speed is [51] Int. Cl. ..G0lp 3/48represented by a pulse source providing pulses leaving Field of Searchfrequency proportionate to cable speed, the frequency is converted intoa voltage to be compared with a reference for indicator control.

8 Clalms, 1 Drawing Figure ACE Cab/f PATENTEnJum I972 4rraA/var parentthat they affect unfavorably the electrical properties of the cable. Forexample, faults in the conductor increase reflections therein. It istherefor necessary to carefully avoid such defects, or at least to keepthem within acceptable tolerances.

Heretofore, however, there existed defects which were detected onlyafter the cable had left the production line and was, supposedlycompleted. Measurements conducted thereafter, as to the electricalcharacteristics of the cable, permitted only rather belatedly detectionof such defects as well as some quantitive analysis thereof. Suchmeasurements, however, do not in themselves indicate the source of theerror. If measured defects or faults as reflected in deviation of thedesired electrical characteristicsof the cable from the actual onesexceed acceptablelimits and if, accordingly, the reflections in thecompleted cable are too high, then the entire cable is actually wasteand has to be discarded as useless. Naturally, this kind of overallmanufacturing procedure with subsequent defect detection in thecompleted cable is rather uneconomical.

We have found now that one of the sources of errors for causing suchdefects is the withdrawal equipment, regardless how constructed, whichengages the cable in a discontinuous, jerky fashion for moving the cablethrough the production line. This holds true regardless of theconstruction of this equipment, as the jerky action stretches and upsetsthe conductive material. Moreover, such discontinuous and jerkyengagement of the cable by the withdrawing and transporting equipment isnot necessarily uniform as far as it effects the cable and wear and tearof the equipment may build up slowly.

The problem to be solved by the invention, therefore, is to find amethod in which the production of defects in the cable can already beascertained during manufacturing thereof and fast enough so that thecause and source for such defects can be pinpointed immediately and atan high degree of accuracy. This problem is solved, according to theinvention, in that the speed of the cable is supervised by representingthe propagation of the cable through the production line as a pulsesequence. The pulse rate represents the cable speed on an instantaneousbasis. A pulse generator engages the cable directly or parts of theproduction line which move with the same speed as the cable.

We found in particular that, whenever pulse generation became irregularcorresponding to a momentary speed deviation of the cable from theproper regular and overall uniform propagation speed, defects have beenproduced. The detection then of deviation of pulse spacing from regularspacing is a suitable modality to detect defects at an early stage.Moreover, it was found that the instantaneous pulse rate or frequencyshould be converted into a proportional voltage to provide an analogrepresentation of the cable speed. Voltage variations in a high speedconverter are sufficiently fast and responsive to cable speed variationsas a result of local jerky interaction with the withdrawal equipment.The pulse generator is, therefore, connected to apulse-frequency-to-voltage converting device having several measuringranges and which provides voltage that is proportional to the frequencyof the pulse source. A particular output voltage can be taken from apotentiometer connected to that converter. A recorder is connected tothe potentiometer, together with a voltage source which provides avoltage oppositely equal and constant to the voltage provided byconverter and potentiometer so that there is complete compensation, ifthe speed of the cable as represented by pulse frequency and outputvoltage of the converter, equals the constant reference voltage. Speeddeviations of the cable result in similar voltages as applied to therecorder and for all measuring ranges of the converter.

The invention has the advantage that not only is there instantaneous andcontinuous supervision of production of the cable, but the location ofsuch supervision can be chosen without restraint, because withoutdifficulties the pulse source can be provided anywhere in the cablewithdrawing equipment or even in engagement with the cable itself. Forexample, the pulse source can be located in the vicinity of interactionof the cable with the withdrawing equipment, so that local speeddeviations can readily be detected.

Another advantage is to be seen in that the potentiometer can beadjusted in accordance with selection of difiering operating ranges ofthe converter, so that the same voltage range is available for the inputof the recorder, regardless of the chosen converter, and the samerecording scale can be used accordingly.

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter which is regarded as theinvention, it is believed that the invention, the objects and featuresof the invention and further objects, features and advantages thereofwill be better understood from the following description taken inconnection with the accompanying drawings in which:

The FIGURE illustrates somewhat schematically equipment to be used forpracticing the invention.

Proceeding now to the detailed description of the drawings, there is apulse source 1 connected by means of a line 2, to a converter 3. Pulsesource 1 may, for example, include a compensating roller and it scansalong the surface of an HF cable as propagating through a productionline. Alternatively, pulse source 1 may be attached to parts moving atsame speed as the HF cable to be tested. For example, a shaft of thecablewithdrawal disc itself maybe constructed to serve as pulse source.

The pulse source is provided so that it furnishes a relatively largequantity of pulses in representation of cable propagation, for example,10,000 pulses per revolution of the compensating roller, of awithdrawing disc etc. The pulse source will include a rotating part anda stationary scanner, converting the sequential presentation of indiciaof the rotating part into a sequence of electrical time-spaced pulses.Converter 3 receives the pulses, and the spacing in between is afaithful replica of the propagation of the cable. Converter 3 respondsparticularly to the frequency of the pulses and provides a voltage whichis proportional to the pulse frequency.

The output voltage of converter 3 is provided across a potentiometer 4.A source 5 of constant reference potential, is connected in series withan adjustable portion of potentiometer. The voltage that can be takenfrom the potentiometer 4 is subtracted from the reference voltage orvice versa and the difference is applied to a galvanometer 6 as well asto the input terminals of a recording type instrument 7, for example, achart recorder. Galvanometer 6 and recorder 7 are connected in parallelto each other.

During operation source 1 provides pulses which in sequence and as tospacing of sequential ones represent cable propagation through theproduction line. These pulses are correspondingly provided with aparticular instantaneous frequency which directly represents the rate ofadvance of the cable, and the converter 3 provides a voltage that isproportional to that speed. For example, 10,000 pulses per unit time areto be provided by source 1 when the cable has the desired speed. Theoutput voltage of converter 3 is fed across the entire resistor portionof the potentiometer 4, but the measuring voltage to be used is takenfrom between one terminal and the adjustable tab or glider of thepotentiometer. That voltage is compared with the reference voltage asprovided by source 5 and, as stated above, the difference operates therecorder 7 as well as galvanometer 6.

It is now desirable that galvanometer as well as recorder operateswithin the same range for different ranges of the converter 3, and forthis, potentiometer 4 is adjusted prior to beginning of measurement to aparticular value obtained as follows. A calibrated reference pulsesource is connected to converter 3 in lieu of cable propagationresponsive source 1. The calibrated pulse source, for example is an RCgenerator and is presumed to provide l0,000 pulses per unit time. Theconverter 3 is now trimmed so that for its smallest measuring range thisfrequency corresponds to an output, for example, of exactly 20 volts. Ifthe measuring ranges are changeable at a ratio l:2:4:8, then for thesame input frequency and upon switching the converter to the next highermeasuring range, output voltages respectively of 10, 5 and 2.5 voltswill be produced by the converter. Potentiometer 4 is now being adjustedfor each and all measuring ranges so that in each case 2.5 volts canvbetaken from it. Voltage source 5 provides a constant reference voltage ofprecisely 2.5 volts and is connected in polarity opposition.

Now the auxiliary reference pulse source is disconnected from the systemand pulse source 1 is connected to the input of converter 3. If, now thecable has speed that in fact 10,000 pulses are furnished by source 1 perunit time, 2.5 volts can be taken from potentiometer 4 which are fullycompensated by the 2.5 volts of the source 5 of reference voltage.Accordingly, galvanometer 6 indicates and recorder 7 plots along zeroline. A still permissible speed error of cable withdrawal of ipercent,should it occur, produces for all measuring ranges of the converter 3 avoltage of t 0.125 volts as applied to instruments 6 and 7. Thiscorresponds to a particular deflection of the galvanometer needle aswell as to a particular excursion in the curve as plotted by recorder 7.

If the speed of the cable deviates from that desired speed, theproportional voltage applied to potentiometer 4 changes and the voltagetaken from the potentiometer changes accordingly. Source 5 providesconstant reference voltage so that galvanometer 6 now shows andeflection and a corresponding deflection will be registered on thechart plotted by device 7. The circuit in accordance with the figure ofthe drawing is constructed so that after it has been calibrated once,the recording device ascertains variations in the speed of the cableonly; such deviations and errors are indicated, as well as recorded, asan immediate presentation of disturbing influences upon the cableadvance.

The recording device should, for example, indicate limits for defining acritical range within which a cable error still remains tolerable. Inother words, if was found that reflections in a cable can be toleratedup to a point, and the defects in the cable corresponding to thattolerance limit correspond to cable speed irregularities duringproduction within a particular range. It is therefore readilyascertainable from the chart whether or not there is a tendency for theerror to increase beyond these limits. Should the speed error exceedthose limits cable production can be stopped immediately. The source ofthe speed error can readily be ascertained, for example, by correlatingthe curve as plotted by writer 7 with the equipment operation permittingnow elimination of this potential source for the production of adefective and faulty cable.

In accordance with an additional feature of the invention the measuringdevice 7 may be provided with equipment, for example, with optical oracoustical transducers, responding when the speed error begins to exceedthe acceptable limit, so that the operating personnel is immediatelyalerted and appraised of such situation. One could also provide therecording device directly with an operating contact; as soon as amaximum limit has been reached it actually turns off the manufacturingfacilities automatically.

The invention is not limited to the embodiments described above but allchanges and modifications thereof not constituting departures from thespirit and scope of the invention are intended to be included.

I claim:

l. The method of indirectly detecting local defects in an HF cable as ittraverses and propagates through a production line comprising the ste sof:

deriving a p se sequence from the production line, faithfullyrepresenting the propagation of the cable through the production line,the frequency of the pulses in the sequence representing cable speed;

converting the frequency of the pulses in the sequence into a signalvoltage in representation of cable speed;

providing a compensating voltage for the voltage signal inrepresentation of a uniform, desired cable speed; and

providing a running visible indication of deviation of the frequencydependent; cable speed representing signal from the compensating voltagein representation of momentary speed deviations of the cable from thedesired speed including particularly periodically recurring speeddeviations in representation of defect causing, upsetting andstretching-recurring influences in the cable.

2. The method as in claim 1, the running indication being provided as aplotted curve on a chart, from which speed deviation and deviationtendencies are ascertainable.

3. The method as in claim 1, and including the step of providing analerting indication when the speed deviation exceeds predeterminedlimits.

4. Method as in claim 1, the converting step being preceded by a step(a) of selecting a frequency-to-voltage conversion range, and by step(b) of preadjusting the converted voltage commensurate with the fixedcompensating voltage as separately derived.

5. The method as in claim 1, the converting step including utilizationof a multi-measuring range device and a potentiometer connected acrossthe output of the device to obtain frequency and cable speed indicatingoutput that is independent from the measuring range.

6. Apparatus for indirectly detecting defects in an HF cable as ittraverses and propagates through a production line, comprising aproduction line traversed by said cable propagating therethrough;

first means for deriving a pulse sequence from the production linefaithfully representing the propagation of the cable through theproduction line the frequency of the pulses in the sequence representingcable speed;

second means having plural adjustable measuring ranges and beingconnected to the first means for converting the frequency of the pulsesin the sequence into a signal voltage in representation of cable speed,the second means having output terminals across which the signaldevelops;

third means for providing a constant compensating voltage for thevoltage signal in representation of a uniform, desired cable speed;

a potentiometer with adjustable tap, connected across the terminals andhaving its adjustable tap connected to the third means, the tap adjustedcorresponding to the selected measuring range of the second means sothat the output voltage taken from the potentiometer and compared withthe compensating voltage represents the desired cable speedindependently from the selected measuring range; and

fourth means connected to one of the terminals of the potentiometer andto the third means for providing a running indication of deviation ofthe frequency dependent signal from the compensating voltage inrepresentation of momentary speed deviations of the cable from thedesired speed in further representation of defect-causing, upsetting andstretching influences in the cable.

7. Apparatus as in claim 6, the fourth means including a recorder.

8. Apparatus as in claim 6, the fourth means including a galvanometer.

t I 4 i k

1. The method of indirectly detecting local defects in an HF cable as ittraverses and propagates through a production line comprising the stepsof: deriving a pulse sequence from the production line, faithfullyrepresenting the propagation of the cable through the production line,the frequency of the pulses in the sequence representing cable speed;converting the frequency of the pulses in the sequence into a signalvoltage in representation of cable speed; providing a compensatingvoltage for the voltage signal in representation of a uniform, desiredcable speed; and providing a running visible indication of deviation ofthe frequency dependent; cable speed representing signal from thecompensating voltage in representation of momentary speed deviations ofthe cable from the desired speed including particularly periodicallyrecurring speed deviations in representation of defect causing,upsetting and stretchingrecurring influences in the cable.
 2. The methodas in claim 1, the running indication being provided as a plotted curveon a chart, from which speed deviation and deviation tendencies areascertainable.
 3. The method as in claim 1, and including the step ofproviding an alerting indication when the speed deviation exceedspredetermined limits.
 4. Method as in claim 1, the converting step beingpreceded by a step (a) of selecting a frequency-to-voltage conversionrange, and by step (b) of preadjusting the converted voltagecommensurate with the fixed compensating voltage as separately derived.5. The method as in claim 1, the converting step including utilizationof a multi-measuring range device and a potentiometer connected acrossthe output of the device to obtain frequency and cable speed indicatingoutput that is independent from the measuring range.
 6. Apparatus forindirectly detecting defects in an HF cable as it traverses andpropagates through a production line, comprising a production linetraversed by said cable propagating therethrough; first means forderiving a pulse sequence from the production line faithfullyrepresenting the propagation of the cable through the production linethe frequency of the pulses in the sequence representing cable speed;second means having plural adjustable measuring ranges and beingconnected to the first means for converting the frequency of the pulsesin the sequence into a signal voltage in representation of cable speed,the second means having output terminals across which the signaldevelops; third means for providing a Constant compensating voltage forthe voltage signal in representation of a uniform, desired cable speed;a potentiometer with adjustable tap, connected across the terminals andhaving its adjustable tap connected to the third means, the tap adjustedcorresponding to the selected measuring range of the second means sothat the output voltage taken from the potentiometer and compared withthe compensating voltage represents the desired cable speedindependently from the selected measuring range; and fourth meansconnected to one of the terminals of the potentiometer and to the thirdmeans for providing a running indication of deviation of the frequencydependent signal from the compensating voltage in representation ofmomentary speed deviations of the cable from the desired speed infurther representation of defect-causing, upsetting and stretchinginfluences in the cable.
 7. Apparatus as in claim 6, the fourth meansincluding a recorder.
 8. Apparatus as in claim 6, the fourth meansincluding a galvanometer.